This invention relates to animal feeds, and more particularly to an improved animal feed composition and method of compounding animal feed utilizing a reactive magnesium oxide, in conjunction with a binder, as a lubricant in the extrusion of animal feed pellets.
Animal feeds are generally produced with low cost byproduct ingredients. These ingredients ate often dusty, unpalatable, of low density, and have inadequate nutrient profile. To correct these shortcomings, ingredients are combined into a mixture with the necessary vitamins, minerals, and amino acids to meet the nutrient requirements of the animals. This is normally accomplished by extrusion and/or compaction techniques to form pellets, blocks, or briquettes. Extrusion and compaction eliminate ingredient segregation, increase bulk density, reduce dust, mask unpalatable ingredients, and reduce wastage.
The pelleting process consists of proportioning ingredients to meet the desired nutrient specifications, mixing, conditioning the mixture with steam, and extruding the conditioned meal through a die. Resistance in the die provides compaction necessary to form the pellet. Different ingredients will affect the resistance to extrusion and thereby affect pellet durability and production efficiency. Low resistance may require a binding agent while excessive resistance may require a lubricant.
Commercial pellet binders may be added to animal feeds to help maintain the physical integrity of the feed pellets. Chemically reactive binders have been used, as set forth in U.S. Pat. No. 4,996,065 (Van de Walle). These binders rely on a mixture of metal oxides and phosphates which react during pelleting to produce a metal phosphate cement-type compound which sets and strengthens the pellet. Alternately, metal oxides have been combined with liquid molasses to form "gels" which lock ingredients together into a solid block, as described in Canadian Patent 1,206,368 (Graham).
Lignosulfonates have also been used as binders in the manufacture of animal feed pellets, as described in U.S. Pat. No. 3,035,920 (Knodt), Canadian Patent 1,203,414 (Ashore), and U.S. Pat. No. 5,281,434 (Winowiski). The trend has been to enhance the binding potency of the lignosulfonate to allow lower use of levels in the feed. This concentration has been at the expense of lubricity that often accompanied the less refined lignosulfonates.
Lubricants have been added to feeds to reduce resistance to extrusion and increase production efficiency. Examples of commonly used lubricants include fats, oils, gums, and talc. Reduction of resistance in the die is generally accompanied by loss of pellet hardness or durability due to reduced compression. This loss of physical strength ultimately leads to an increased percentage of pellets reverting to meal. Thus, the use of binders referred to previously in combination with lubricants correct this deficiency.